Justin Mates joined the County Executive’s Office in 2019 as a Deputy CEO. In that role, he helped coordinate the work of the County’s community services departments such as Public Works and Planning & Building in providing municipal services to County unincorporated areas.  He also oversaw interdepartmental efforts such as the Farmworker Housing Compliance Task Force and the Safe Trailer Parks Program. During the COVID-19 pandemic, Justin served in the Emergency Operations Center and led a number of response efforts, including the County’s community testing and vaccination programs. He first joined the County in 2012 as a deputy in the County Attorney's Office where he advised nearly every County department on a range of legal issues, including affordable housing, real estate, taxes and public finance, intergovernmental transactions and general litigation. In 2018, he served as the County’s real property manager overseeing all transactions and strategy for the County’s real estate portfolio.

As Assistant County Executive, his responsibilities include working with the Center on Homelessness to reach the Board of Supervisors’ goal of “functional zero” as well as managing countywide and cross-jurisdictional initiatives.

Prior to joining the County, Justin worked for an international development nonprofit and as an attorney in private practice. He received his bachelor’s degree in political science from Stanford University with distinction and honors and his J.D. magna cum laude from Harvard Law School. He lives in San Mateo County with his wife and three children.

Department Assignments

Health; Housing; Human Services Agency.

To reach Justin's Executive Assistant, please email Julianne Concepcion at jrconcepcion@smcgov.org